A description is given of how edge erase of prismatic objects appear through a television camera serving as visual input to a computer. Two types of edge-finding predicates are proposed and compared, one linear in intensity, the other non-linear. A statistical analysis of both is carried out, assuming input data distorted by a Gaussian noise. Both predicates have been implemented as edge-verifying procedures, ie. Procedures aiming at high sensitivity and limited to looking for edges when approximate location and directions are given. Both procedures have been tried on actual scenes. Of the two procedures the non-linear one emerged as a satisfactory solution to line-verification because it performs well in spite of surface irregularities.
